fix: fix setBean single binding write and add tests

flow-data/src/main/java/com/vaadin/flow/data/binder/Binder.java

@@ -1916,10 +1916,15 @@ public static <BEAN> Binder<BEAN> withPropertySet(
     }
 
     /**
-     * Informs the Binder that a value in Binding was changed. This method will
-     * trigger validating and writing of the whole bean if using
-     * {@link #setBean(Object)}. If using {@link #readBean(Object)} only the
-     * field validation for the given Binding is run.
+     * Informs the Binder that a value in Binding was changed.
+     *
+     * If {@link #readBean(Object)} was used, this method will only validate the
+     * changed binding and ignore state of other bindings.
+     *
+     * If {@link #setBean(Object)} was used, all pending changed bindings will
+     * be validated and non-changed ones will be ignored. The changed value will
+     * be written to the bean immediately, assuming that Binder-level validators
+     * also pass.
      *
      * @param binding
      *            the binding whose value has been changed
@@ -1930,20 +1935,7 @@ protected void handleFieldValueChange(Binding<BEAN, ?> binding) {
         if (getBean() == null) {
             binding.validate();
         } else {
-            BinderValidationStatus<BEAN> status = validateBindingsAndBean();
-            if (status.isOk()) {
-                doWriteIfValid(getBean(), changedBindings);
-            } else {
-                // Fire status change for changed bindings only
-                getValidationStatusHandler()
-                        .statusChange(new BinderValidationStatus<>(this,
-                                status.getFieldValidationStatuses().stream()
-                                        .filter(s -> changedBindings
-                                                .contains(s.getBinding()))
-                                        .collect(Collectors.toList()),
-                                status.getBeanValidationErrors()));
-                fireStatusChangeEvent(status.hasErrors());
-            }
+            doWriteIfValid(getBean(), changedBindings);
         }
     }
 
@@ -2229,9 +2221,13 @@ public <FIELDVALUE> Binding<BEAN, FIELDVALUE> bindReadOnly(
      * back to their corresponding property values of the bean as long as the
      * bean is bound.
      * <p>
-     * Any change made in one of the fields also runs validation for all the
-     * fields {@link Binding} and bean level validation for this binder (bean
-     * level validators are added using {@link Binder#withValidator(Validator)}.
+     * Note: Any change made in one of the bound fields runs validation for only
+     * the changed {@link Binding}, and additionally any bean level validation
+     * for this binder (bean level validators are added using
+     * {@link Binder#withValidator(Validator)}. As a result, the bean set via
+     * this method is not guaranteed to always be in a valid state. If bean
+     * validity is required at all times, {@link #readBean(Object)} and
+     * {@link #writeBean(Object)} should be used instead.
      * <p>
      * After updating each field, the value is read back from the field and the
      * bean's property value is updated if it has been changed from the original
@@ -2801,28 +2797,6 @@ protected BinderValidationStatus<BEAN> validate(boolean fireEvent) {
         return validationStatus;
     }
 
-    /**
-     * Runs validation for all bindings to determine binder's validity state. If
-     * a bean has been set and all bindings pass validation, bean-level
-     * validations are run as well.
-     *
-     * @return BinderValidationStatus for the validation run
-     */
-    private BinderValidationStatus<BEAN> validateBindingsAndBean() {
-        List<BindingValidationStatus<?>> bindingStatuses = validateBindings();
-        boolean bindingsInError = bindingStatuses.stream()
-                .anyMatch(BindingValidationStatus::isError);
-
-        List<ValidationResult> beanStatuses = new ArrayList<>();
-        // Only execute bean-level validation when binding validators pass
-        if (!bindingsInError) {
-            beanStatuses.addAll(validateBean(getBean()));
-        }
-
-        return new BinderValidationStatus<>(this, bindingStatuses,
-                beanStatuses);
-    }
-
     /**
      * Runs all currently configured field level validators, as well as all bean
      * level validators if a bean is currently set with

flow-data/src/main/java/com/vaadin/flow/data/binder/BinderValidationStatus.java

@@ -34,6 +34,10 @@
  * Note: if there are any field level validation errors, the bean level
  * validation is not run.
  * <p>
+ * Note: if the status change is triggered via automatic validation due to a
+ * changed field value, the field validation statuses will only cover the
+ * changed fields.
+ * <p>
  * Use {@link Binder#setValidationStatusHandler(BinderValidationStatusHandler)}
  * to handle form level validation status changes.
  *

flow-data/src/test/java/com/vaadin/flow/data/binder/BinderTest.java

@@ -2230,6 +2230,62 @@ public void setBean_readOnlyBinding_accessorsBiding_valueIsNotUpdated() {
         Assert.assertSame(val, bean.getVals());
     }
 
+    @Test
+    public void setBean_oneBindingValidationFails_otherBindingValueShouldBeSet() {
+        binder.forField(nameField).withValidator(
+                (value, context) -> ValidationResult.error("Always fails"))
+                .bind(Person::getFirstName, Person::setFirstName);
+        binder.forField(ageField)
+                .withConverter(new StringToIntegerConverter(""))
+                .bind(Person::getAge, Person::setAge);
+
+        binder.setBean(item);
+
+        ageField.setValue("15");
+
+        assertEquals(
+                "Age should have been set regardless of invalid name field.",
+                15, item.getAge());
+    }
+
+    @Test
+    public void setBean_oneBindingRequiredButEmpty_otherBindingValueShouldBeSet() {
+        item.setFirstName(null);
+
+        binder.forField(nameField).asRequired("Name is required")
+                .bind(Person::getFirstName, Person::setFirstName);
+        binder.forField(ageField)
+                .withConverter(new StringToIntegerConverter(""))
+                .bind(Person::getAge, Person::setAge);
+
+        binder.setBean(item);
+
+        ageField.setValue("15");
+
+        assertEquals(
+                "Age should have been set regardless of required but empty name field.",
+                15, item.getAge());
+    }
+
+    @Test
+    public void setBean_binderValidationFails_noValueShouldBeSet() {
+        binder.forField(nameField).bind(Person::getFirstName,
+                Person::setFirstName);
+        binder.forField(ageField)
+                .withConverter(new StringToIntegerConverter(""))
+                .bind(Person::getAge, Person::setAge);
+
+        binder.withValidator(
+                (value, context) -> ValidationResult.error("Always fails"));
+        binder.setBean(item);
+
+        ageField.setValue("15");
+
+        assertEquals(
+                "Age should not have been set since binder validation fails.",
+                32, item.getAge());
+    }
+
     @Test
     public void invalidUsage_modifyFieldsInsideValidator_binderDoesNotThrow() {
         TestTextField field = new TestTextField();